The components of an injection molding system typically include a stock supply assembly, an extruder assembly, an injection assembly, a mold and a clamping assembly. In a typical molding process, the stock supply assembly supplies a certain amount of stock material to the extruder assembly. The extruder assembly processes or plasticizes the stock material into injection material, and conveys the desired amount of material to the injection assembly. Upon clamping of the mold within the clamping assembly under the force necessary for successful molding, the injection assembly injects the injection material into a mold cavity within the mold.
The mold is usually formed by two joinable/separable mold portions. When an insert molding procedure is used in an injection molding machine, the mold portions are initially separated and an unfinished insert or work piece is loaded into one of the mold portions. The mold portions are then joined together to form the mold cavity.
Once the mold cavity is formed, the mold is clamped under the necessary force to hold the unfinished insert or work pieces in position during operation of the injection assembly, which injects the molding material into the mold cavity. A portion of the mold is then opened or removed and the molded product having the previously unfinished, now molded part and insert or joined work pieces, are unloaded from the mold cavity.
In the past, the molding of separate elongate molded or extruded pieces to form a single part has been performed using adhesives. The use of adhesives for joining such parts has the disadvantage that undesirable fumes or other materials may result from the use of such adhesives. Also, the use of adhesives at an operator work station typically results in messy work stations. Still further, cosmetic improvements may be required to be made to the parts once they are joined by the adhesives.
Alternatively, separate machined or cast molds have been used which provide components for receiving the work pieces to be joined together. Such molding processes may result in an unattractive "step off" or discontinuous joint line between the work pieces being molded and the molded joint material. Also, conventional molding procedures typically require additional finish processing to remove flash from the articles. The formation of flash, and its removal, result in increased costs due to wasted material, and the additional labor required to remove or deflash the articles for finishing. In either of these operations, an additional quality control inspection of each article may also be required, which further increases overall labor expense.